There are several things you can try depending on where you are located. First, I would suggest scouring the community colleges in your area for ADN programs. I know of eight nursing schools within ninety miles of where I live, so it is likely that you can find something that will suit you better. Also, the thing that I found to be difficult when choosing my school was that while I could get into major universities, the nursing programs there tend to have a longer waiting list for applicants. That's my main reason for choosing a two year college to attend. I would have liked to attend The University

but when it came down to my age and what I wished to gain from school, the decision to wait on a two + year waiting list just wasn't in the cards. As I, like you, had been out of school for a long time before deciding to go back, it made for some apprehension on my part as to my ability to remember what I needed to that far down the road. It turned out it took a little getting used to, but after I got rolling school was a breeze. Your age will serve as a much better ally to you in regard to education than you think it will if you are anything like me. The difference is drive and the ability to understand the difference between your old self and your current self. The thought you knew everything kid and want to know everything man. Again, that's how it was for me.
However, I would suggest that if you have not already done so to go have a long sit down with the advisor for the nursing program and explain your concerns. I have found that communicating with them as an adult results in "tricks" or "advantages" which you may not be aware. Remember, it's what they do for a living and having someone that actually wants their advice, rather than staring at the wall and tuning them out, will net you much more information and possibilities than you think.
Good luck, and take the ACT again. Just find a tutor or study guide to review before you go. You should have no trouble increasing your score the amount necessary for the requirement. The logic of an adult is a great asset when taking those exams.